only enable usage of memalign on GNU/Linux
Fix #745 - simd::compare_less QOI

compare_less algorithm on SSE/AVX targets was suboptimal as it
was reversing bits after computing the bitmask while reversing
elements using shuffle then compute bitmasks is more efficient
, lead to better inlining of compare_less based code and some
code refactoring using reverse and hmsb.
correcting round test not to assume double support. The tests are moved in the REAL_TYPES
section
Merge pull request #792 from jtlap/round_unit_tests

correcting round test not to assume double support. The tests are moved ...
Define correct number of output elements in sum bench
Add outer sum benches
add special code to detect posix_memalign on mac os x, fix #788
only add directories when filling NT2_MODULES, avoid adding manifest files for in-source builds
add message to cmake if building in-source
Replace inner_fold_step by fold_step
Replace outer_fold_step by fold_step
Move target_type_from_site in a proper file, increase parallelism of outer_fold
Forget call fold spawner in ibound leftover
Remove use of fold_step in simd outer_fold
Remove call of fold_step in scalar outer_fold
Change loop order to improve cache locality
Call of transform spawner for outer_fold in inner_bound
Update outer_fold.hpp
Factorize code of incache outer_fold by using outer_fold_step
Continue the factorization